1. Field of the Invention
The present invention relates generally to aseptic structural ribs for plastic containers, and more particularly to structural ribs that prevent ovalization of a plastic container and work with aseptic sterilization of the plastic container formed by blow molding.
2. Related Art
Conventional structural ribs for plastic containers may meet the strength or structural requirement for a plastic container, but cause problems in sterilization of the resultant containers. In order for a plastic container to be filled with food product, an aseptic process is necessary. During this process, a sterilizing agent first must be introduced to all internal portions of the container and then must be removed in accordance with Food and Drug Administration (FDA) requirements. Conventional structural ribs did not address both the structural and aseptic needs of the plastic container.
Consequently, known structural rib shapes or methods of forming a plastic container with the same either provided sufficient rigidity for the plastic container but did not pass the FDA requirements for the aseptic process, or, provided structural ribs with a geometry that allowed the resultant container to pass the FDA requirements after the aseptic process, but failed to provided sufficient rigidity or strength to the plastic container. As a result, known structural ribs cause a number of plastic containers to fail the aseptic process, or, result in plastic containers filled with food product that develop an undesirable ovalization of the container.
Known structural ribs for a plastic container employ a single indentation toward the center of the plastic container. A single structural rib does not provide the necessary hoop strength or rigidity to prevent ovalization and/or compressing of the container side walls during vending. Deeper projections of the single structural rib were thought capable of providing the necessary strength, but failed to hold the shape of the plastic container during vending. That is, the deeper projections did not resist distortion.
What is needed then is an improved plastic container with at least one structural rib that overcomes shortcomings of conventional solutions.